Studies on Development of Functionalized Biopolymeric Nanocomposite Based Edible Nanocoating on Food Products and Sustainable Secondary Packaging
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In the current century, the rising environmental issues caused by increased carbon footmarks and waste generation from conventional packaging systems have gained concern in developing environment benign polymers based edible and non-edible food packaging systems availed from renewable resources and their modified forms, which can transport the former produce to endusers in a safe condition. Additionally, the use of renewable biomaterials for the fabrication of edible coated food products (a kind of edible food packaging) has become indispensable to reduce the food waste generations. In this context, the present thesis work directs the use of bionanostructures based on modified polysaccharide (iron functionalized cellulose nanofiber, and sodium tripolyphosphate crosslinked nanochitosan) and protein (silk nanodisc) to tailor the inherent properties of biopolymers to be used as edible coating materials on perishable fruit products (a type of primary packaging) and their sustainable secondary packaging (a secondary packaging for edible coated food products) for safe delivery. The cellulose nanofiber (CNF), being fabricated from cellulose, is investigated for developing edible coating on food products. The fabrication of iron functionalized CNF (mgCNF) following single step co-precipitation technique is a way to adsorb iron particles on CNF molecule to be used as a reinforcement in developing chitosan (CS) biocomposites. Additionally, the formulation of curcumin (Cur) (a potential anticancerous agent) loaded mgCNF dispersed CS as edible nanocoating on cut pineapple delivers a tailored-made functionalized nanocomposite for anti-cancerous and iron-fortified ready to eat pineapple fruit products. The anti-cancerous property of edible-nanocoating materials are analysed, where the loading of Cur with CS based biocomposites shows anti-cancer activity by disrupting the cell membrane and further indicates the death of cancer cells with cell viability of ~17% and ~98% for CS/mgCNF (1.5 wt.%) with and without Cur, respectively. Further, the nanocoatings are stable at heat sterilization temperature providing a new approach to treat the edible coated fruit products at high temperatures for obtaining enhanced shelf life. The optical properties and appearance of Cur loaded films provide red and yellow colorant effect with uniform transparency, which can be well known from a*, and b* values, and further increase consumer acceptance. It is noteworthy to mention that the developed edible nanocoating materials help to improve the storage conditions of cut pineapple. Therefore, the study delivers a technique to supplement the iron functionalized food products with anti-cancerous activity and provide improved performance to reduce food waste and, delivery of active compounds. Additionally, the formulated edible nanocoating materials are applied to coat whole kiwifruits and the keeping quality of kiwifruits is analysed during the storage period (10 days and 10 °C). The influence of edible nanocoating on firmness, weight loss analysis, color parameters, and physicochemical properties has been studied. Interestingly, at 10 days of storage, there is noticed a sharp decrease in the firmness of uncoated kiwifruit (~5 N), whereas, the edible coated kiwifruits using Cur-CSmgCNF (1.5 wt%) has maintained the firmness above 15 N till 10 days of storage. Thus, a welldeveloped new edible coating system based on Cur loaded functionalized CNF/CS nanocomposite has been fabricated for perishable food products. However, as discussed, the system has been targeted for iron fortified, anticancerous materials for improving the shelf life of food products. Thus, a simple edible coating system based on nanochitosan (developed by ionic gelation method) modified starch and guar gum biocomposites has been fabricated, which is suited for improving the product life.
Supervisor: Vimal Katiyar